• Journal of Biosystems Engineering
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• v.20 no.4
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• pp.360-367
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• 1995

The effect of air vent holes, stacking methods of boxes and clearance between boxes on static pressure drop, were measured to design of pressure cooling system. Static pressure drops in air vent hole of carton box were measured for different hole opening ratio from 1% to 5%. Static pressure drop was expressed as a function of superficial velocity as second-degree polynomial. At given static pressure in plenum chamber, static pressure drop in boxes was shown as second-degree polynomial of the number of carton box in series stacking method, as first-degree polynomial in height and parallel stacking method. In pressure cooling of 24 boxes of Tsugaru apple, air flow rates through clearance between the boxes were shown 1.27 and 1.65 times than those of through the inside of boxes at the plenum pressure of 10mmAq and 20mmAq, respectively.

• Journal of Korea Foundry Society
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• v.29 no.1
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• pp.38-44
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• 2009

Magnetic separation of Fe contaminated Al-Si cutting chip scraps was performed for the recyclability assessment. It was also aimed to investigate the casting and solidification characteristics of the cutting chip scraps. The magnetically separated cutting chip scraps were adequately treated for the casting procedure and test specimens were made into a stepped mold inducing different cooling rates. The test specimens were evaluated by the combined analysis of ICP, Spectroscopy, OM-image analyzer, SEM/EDS, etc. Solidification characteristics of cutting chip scraps were examined as functions of Fe content and cooling rate. It is concluded that the magnetic separation process can be utilized to recycle the Fe contaminated Al-Si cutting chip scraps in the high cooling rate foundry process.

• Nuclear Engineering and Technology
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• v.29 no.4
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• pp.291-298
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• 1997

In advanced nuclear reactors, the passive containment cooling has been suggested to enhance the safety. The passive cooling has two mechanisms, air natural convection and oater cooling with evaporation. To confirm the coolability of PCCS, many works have been performed experimentally and numerically. In this study, the water cooling test was performed to obtain the evaporative heat transfer coefficients in a scaled don segment type PCCS facility which have same configuration with AP600 prototype containment. Air-steam mixture temperature and velocity, relative humidity and well heat flux are measured. The local steam mass flow rates through the vertical plate part of the facility are calculated from the measured data to obtain evaporative heat transfer coefficients. The measured evaporative heat transfer coefficients are compared with an analytical model which use a mass transfer coefficients. From the comparison, the predicted coefficients show good agreement with experimental data however, some discrepancies exist when the effect of wave motion is not considered. Finally, a new correlation on evaporative heat transfer coefficients are developed using the experimental values.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.405-413
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• 1994

This paper presents the experimental results of aerodynamic drags of model cars. The effects of cooling air on total drag were introduced by using momentum theorem. Vehicle-liked Ahmed body and 1/5 model car were used to evaluate the increments of drags due to the internal flow. The results were compared with momentum theorem and other's experiments and showed good agreements. In the case of Ahmed body, drags were increased by 22% due to the internal flow and decreased linealy by reducing internal air flow rates and inlet areas. The experiments on 1/5 model car with ill-defined air flow passage showed 10% increment of drag. The results of present study showed that cooling drag could be predicted by momentum theorem within small errors.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.53-60
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• 2005

The purpose of this study is to improve energy efficiency of windows in office buildings through the evaluation of their heating, cooling and illumination load. Energy efficiency is influenced by window size which is determined at the early stage of building design. The process of this study is as follows. First, energy performance is analysed according to the various rates of windows through computer simulation (ECOTECT). Then, the annual heating, cooling and illuminating loads according to the different window sizes are compared one another. Results indicated that the optimal window size considering energy efficiency is 50% of the surface area. When the window size is 50% of the surface area, annual maintenance expense is also smallest. Since the cost of cooling is larger than that of heating, too low indoor air temperature in summer is unfavorable based on the reasonable annual maintenance expenses.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.12
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• pp.560-564
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• 2006

ZnO thin films were prepared by RF magnetron sputter deposition on p-Si(100) wafer with various cooling rates of substrate temperature such as the substrates were pre-heated to $400^{\circ}C$ before the deposition and then cooled down naturally or slowly to $300^{\circ}C,\;200^{\circ}C,\;100^{\circ}C$, and R.T. by the temperature controller during the deposition. Crystalline and micro-structural characteristics of the films were investigated by XRD and SEM. ZnO films which cooled down naturally or slowly by the temperature controller during the deposition, especially the film were deposited with cooling down from $400^{\circ}C\;to\;200^{\circ}C$ slowly. showed the most outstanding c-axis preferred orientation.

• Journal of Bio-Environment Control
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• v.2 no.1
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• pp.1-8
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• 1993

Experimental and theoretical analyses were carried out to investigate the heat exchange characteristics of the nutrient solution cooling system utilizing ground water. The material of heat exchanger used in the experiment was polyethylene and the cross-flow type was adapted in which nutrient solution was mixed and ground water unmixed. For the exchanger surface area of 0.33$m^2$ and flow rates of ground water of 1-6$\ell$/min, NTU(number of transfer units) and effectiveness of experimental heat exchanger were 0.1-0.45 and 10-35％, respectively. Therefore these results showed that the hydroponic greenhouse of 1,000$m^2$(300 pyong) with the ground water of 10$m^2$/day could cover about 55-70％ of maximum cooling load in summer.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.155-161
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• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.81-87
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• 1991

In this paper, an attempt has been taken for improving the weldability of wer welds of TMCP steel plate by shielding around weld arc surroundings. The principal results of this experimental investigation can be summarized as follows: 1) The cooling rates resulting from wet wlds with the developed electrode on TMCP steel plate could be lower than that of the non-shieled wet welds. 2) The metallurgical characteristics in umderwater wet welds of TMCP steel plate and the developed electrode could be improved by shielding around weld arc surroundings.

• Journal of Korea Foundry Society
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• v.15 no.6
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• pp.546-557
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• 1995

This study was undertaken to obtain an improved understanding of the effects of alloying elements on the residual amounts of Mg in the melt and on the resultant microstructure of compacted vermicular graphite cast irons, and the influence of alloying elements and cooling rates during solidification on the formation of phosphide eutectics, and on the mechanical properties of compacted vermicular graphite cast irons containing copper, tin, molybdenum for producing pearlitic matrix, and also containing phosphorus and boron for increasing wear resistance were evaluated.